scholarly journals Selected Rhizosphere Bacteria Help Tomato Plants Cope with Combined Phosphorus and Salt Stresses

2020 ◽  
Vol 8 (11) ◽  
pp. 1844
Author(s):  
Gylaine Vanissa Tchuisseu Tchakounté ◽  
Beatrice Berger ◽  
Sascha Patz ◽  
Matthias Becker ◽  
Henri Fankem ◽  
...  

Plants are often challenged by multiple abiotic stresses simultaneously. The inoculation of beneficial bacteria is known to enhance plant growth under these stresses, such as phosphorus starvation or salt stress. Here, for the first time, we assessed the efficiency of selected beneficial bacterial strains in improving tomato plant growth to better cope with double stresses in salty and P-deficient soil conditions. Six strains of Arthrobacter and Bacillus with different reservoirs of plant growth-promoting traits were tested in vitro for their abilities to tolerate 2–16% (w/v) NaCl concentrations, and shown to retain their motility and phosphate-solubilizing capacity under salt stress conditions. Whether these selected bacteria promote tomato plant growth under combined P and salt stresses was investigated in greenhouse experiments. Bacterial isolates from Cameroonian soils mobilized P from different phosphate sources in shaking culture under both non-saline and saline conditions. They also enhanced plant growth in P-deficient and salt-affected soils by 47–115%, and their PGP effect was even increased in higher salt stress conditions. The results provide valuable information for prospective production of effective bio-fertilizers based on the combined application of local rock phosphate and halotolerant phosphate-solubilizing bacteria. This constitutes a promising strategy to improve plant growth in P-deficient and salt-affected soils.

Author(s):  
Rajiv Pathak ◽  
Vipassana Paudel ◽  
Anupama Shrestha ◽  
Janardan Lamichhane ◽  
Dhurva. P. Gauchan

Phosphorous (P) is an essential macronutrient and most soils contain high levels of P. However, its availability to plant is limited by rapid immobilization of phosphorous compounds to insoluble forms and hence plant available forms of P in soils are found in low amounts. Phosphate solubilizing bacteria provide an eco-friendly alternative to convert insoluble phosphates into plant available forms. In the present study, three phosphate solubilizing bacterial isolates (PB-1, PB-4 and VC-01) with visually significant phosphate solubilizing abilities were isolated from tomato rhizosphere soil. In-vitro study in pikovskaya’s agar revealed that isolate PB-1 had the highest phosphate solubilizing ability with a phosphate solubilizing index of 2.08±0.07 followed by isolate VC-01 (1.31±0.09) and PB-4 (1.24±0.08). Isolates were used as bacterial inoculum to assess their ability to promote tomato (Lycopersicon esculentum var. Srijana) seedling and plant growth in in-vitro and greenhouse experiment respectively. Isolate PB-4 showed best growth promotion in seedling assay whereas isolate PB-1 and VC-01 also promoted seedling growth compared to control. In greenhouse experiment however, isolates VC-01 and PB-1 significantly enhanced all parameters (shoot length, root length, shoot and root dry weight) compared to uninoculated control whereas isolate PB-4 had a positive effect on all parameters except root length.Kathmandu University Journal of Science, Engineering and TechnologyVol. 13, No. 2, 2017, page: 61-70


Author(s):  
V.Z. Nguyen ◽  
T.O. Dao ◽  
T.H. Nguyen ◽  
E.A. Kalashnikova

Перец овощной (Capsicum annuum L.) является одной из основных возделываемых культур Вьетнама в связи с широким его использованием в пищевой промышленности в качестве приправы. Это делает данное растение важной сельскохозяйственной культурой, которая приносит значительный доход вьетнамским фермерам. Однако на плантациях перца часто наблюдается появление и развитие болезни ризоктониоз, которую вызывает патогенный гриб Rhizoctonia solani, а также наблюдается бактериальное увядание, вызываемое бактерией Ralstonia solanacearum. Поражение ризоктониозом, одной из самых вредных болезней перца, может наблюдаться в любой фазе развития растений. Известно, что ризобактерии способны не только стимулировать рост растений, но и подавлять развитие болезней. Цель данной работы выделение из ризосферы растений перцев бактерий, ингибирующих развитие Rhizoctonia solani и оценка in vitro их фосфатрастворяющей активности и секреции сидерофора. Из различных почвенных образцов, отобранных с полей коммун Ан Хань, Ан Нинь, Кунь Ми, района Кунь Фу, провинции Тхай Бинь, выделено 48 штаммов бактерий, из которых были отобраны 5 штаммов (АТ 16 VK 4.7 VK 4.8 VK 4.12 VK 4.13), обладающих высокой ингибирующей активностью по отношению к Rhizoctonia solani, которая составила 11,11 62,22. Показано, что эти штаммы обладают способностью синтезировать такой фитогормон, как индолилуксусную кислоту (ИУК) (с 9,54 мг/мл до 31,06 мг/мл), растворять труднорастворимые фосфатные соединения и секрецировать сидерофор. Из 5 выделенных штаммов только у штамма АТ 16 данные способности выражены более сильно. Полученные результаты свидетельствуют о том, что изученные штаммы обладают хорошим потенциалом для использования их в качестве биологических агентов, контролирующих развитие R. solani на растениях перца.Peppers or chilli (Capsicum annuum L.) is widely grown in Vietnam because they bring considerable income to farmers. On pepper fields, diseases such as rhizoctonia, Rhizoctoniasolani caused by fungus, bacterial wilt by Ralstoniasolanacearum are often observed. Rhizoctoniasolani causes a wide range of significant diseases such as collar rot, root rot, damping offin horticultural and field crops.The diseases caused by rhizoctonia are one of the most harmful diseases on peppers, can be observed in any phase of plant development. Rhizobacteria that stimulate plant growth can be used to improve plant growth and suppress plant diseases. The purpose of this work is to isolate bacteria from the pepper rhizosphere that inhibit Rhizoctoniasolani and evaluate in vitro their phosphate solubilizing activity and production of siderophore. Of the different soil samples taken from the pepper fields of An Thanh, An Ninh, Quynh My, QuynhPhudistrict, ThaiBinh province, 48 bacterial strains were isolated. Of these, 5 strains (AT16, VK 4.7, VK 4.8, VK 4.12, VK 4.13) expressed as higher inhibitory Rhizoctoniasolani activity were selected. Their inhibitory activity is from 11.11 to 62.22. These strains have the ability to synthesize phytohormone IAA (from 9.54 g / ml to 31.06g / ml), solubilize the phosphate compounds and productsiderophore. Strain AT16 more effective expresses these abilities in comparison with 4 other strains. These results suggest that the selected strains have excellent potential for use as biologically controlled agents of R. solani on pepper plants (Capsicum annuum L.).


2021 ◽  
Vol 9 (9) ◽  
pp. 1935
Author(s):  
Chuansheng Mei ◽  
Robert L. Chretien ◽  
B. Sajeewa Amaradasa ◽  
Yimeng He ◽  
Amy Turner ◽  
...  

Phosphate is one of the most important nutrients for plant growth and development, and only 0.1% of the phosphate in soils is available to plants. Currently, the use of excess phosphate fertilizer has caused surface and ground water pollution and water eutrophication, resulting in algal blooms in lakes and oceans. Therefore, it is imperative to explore alternative ways to solve these problems for sustainable agricultural production and improvement of soil fertility, while protecting the environment. Microorganisms from the rhizosphere and within plants are able to solubilize insoluble soil phosphate, making it available to plants. Five high phosphate solubilizing bacteria from our bacterial endophyte library were chosen for this study and identified as Pantoea vagans IALR611, Pseudomonas psychrotolerans IALR632, Bacillus subtilis IALR1033, Bacillus safensis IALR1035 and Pantoea agglomerans IALR1325. All five bacteria significantly promoted tall fescue growth in vitro. Greenhouse experiments showed that IALR1325 significantly promoted pepper and tomato growth, and IALR632 was the best in promoting tomato growth. In addition, all these bacteria had extracellular acid phosphatase and phytase activities. One of the mechanisms for phosphate solubilization by bacteria is pH reduction caused by gluconic acid production. Our results indicate that P. agglomerans IALR1325 is a promising bacterium for future applications.


2021 ◽  
Vol 11 (3) ◽  
pp. 1034
Author(s):  
Souhila Kerbab ◽  
Allaoua Silini ◽  
Ali Chenari Bouket ◽  
Hafsa Cherif-Silini ◽  
Manal Eshelli ◽  
...  

There is a great interest in mitigating soil salinity that limits plant growth and productivity. In this study, eighty-nine strains were isolated from the rhizosphere and endosphere of two halophyte species (Suaeda mollis and Salsola tetrandra) collected from three chotts in Algeria. They were screened for diverse plant growth-promoting traits, antifungal activity and tolerance to different physico-chemical conditions (pH, PEG, and NaCl) to evaluate their efficiency in mitigating salt stress and enhancing the growth of Arabidopsis thaliana and durum wheat under NaCl–stress conditions. Three bacterial strains BR5, OR15, and RB13 were finally selected and identified as Bacillus atropheus. The Bacterial strains (separately and combined) were then used for inoculating Arabidopsis thaliana and durum wheat during the seed germination stage under NaCl stress conditions. Results indicated that inoculation of both plant spp. with the bacterial strains separately or combined considerably improved the growth parameters. Three soils with different salinity levels (S1 = 0.48, S2 = 3.81, and S3 = 2.80 mS/cm) were used to investigate the effects of selected strains (BR5, OR15, and RB13; separately and combined) on several growth parameters of wheat plants. The inoculation (notably the multi-strain consortium) proved a better approach to increase the chlorophyll and carotenoid contents as compared to control plants. However, proline content, lipid peroxidation, and activities of antioxidant enzymes decreased after inoculation with the plant growth-promoting rhizobacteria (PGPR) that can attenuate the adverse effects of salt stress by reducing the reactive oxygen species (ROS) production. These results indicated that under saline soil conditions, halotolerant PGPR strains are promising candidates as biofertilizers under salt stress conditions.


2021 ◽  
Author(s):  
Hezekiah Korir ◽  
Nancy W. Mungai ◽  
Victor W. Wasike

Abstract Use of phosphate solubilizing bacteria (PSB) and rhizobia can have a positive effect on the growth of common bean. This study aimed at determining the mechanisms of action of native bacterial strains; and to determine their effect in enhancing growth of common bean. The strains were screened for their ability to solubilize insoluble inorganic phosphates and production of indole acetic acid in vitro. A greenhouse experiment was set up to evaluate the response of common bean to inoculation with selected bacterial strains. Six of the bacterial isolates tested showed a positive result for IAA production. Rhizobium pusense showed the greatest solubilization efficiency of 648 followed by Bacillus megaterium (322.3) and Rhizobium phaseoli (308.7). Inoculation of common bean with Rhizobia and PSB had a significant effect on the number of nodules per plant. The highest shoot biomass was observed when Rhizobium phaseoli was co-inoculated with P. polymyxa (4.3g plant-1) compared to the single Rhizobium phaseoli inoculation (1.14 g plant-1). The shoot tissue nitrogen and phosphorous concentration was increased as a results of co-inoculation up to 32.5% and 75.4% respectively. Therefore, tested bacterial strains have great potential in being formulated and used as biofertilizers that can be evaluated under varying field conditions.


2011 ◽  
Vol 52 (No. 3) ◽  
pp. 130-137 ◽  
Author(s):  
H.S. Han ◽  
Supanjani ◽  
K.D. Lee

Biofertilizers have been used as sources to improve plant nutrients in sustainable agriculture. Experiments were conducted to evaluate the potential of phosphate solubilizing bacteria (PSB) Bacillus megaterium var. phosphaticum and potassium solubilizing bacteria (KSB) Bacillus mucilaginosus inoculated in nutrient limited soil planted with pepper and cucumber. Results showed that rock P and K applied either singly or in combination did not significantly enhance soil availability of P and K, indicating their unsuitability for direct application. PSB was a more potent P-solubilizer than KSB, and co-inoculation of PSB and KSB resulted in consistently higher P and K availability than in the control without bacterial inoculum and without rock material fertilizer. Integrated rock P with inoculation of PSB increased the availability of P and K in soil, the uptake of N, P and K by shoot and root, and the growth of pepper and cucumber. Similar but less pronounced results were obtained when rock K and KSB were added concomitantly. Combined together, rock materials and both bacterial strains consistently increased further mineral availability, uptake and plant growth of pepper and cucumber, suggesting its potential use as fertilizer.


Author(s):  
Chandandeep Kaur ◽  
Govindan Selvakumar ◽  
Kaushal Kishore Upreti

The production of weak organic acids by microorganisms has been attributed as the prime reason for the solubilization of insoluble phosphates under both in vitro and soil conditions. Literature seems to be heavily biased towards gluconic acid production by microbes and its subsequent release into the environment as the key factor responsible for phosphate solubilization. This has found credibility since gluconic acid being a product of the Kreb’s cycle is often detected in large quantities in the culture media, when assayed under in vitro conditions. In the present work, the organic acid profiles of four elite phosphate solubilising isolates were determined in the presence of different insoluble sources of phosphates, under in vitro buffered culture conditions by HPLC (High-Performance Liquid Chromatography). While most previous studies did not use a buffered culture media for elucidating the organic acid profile of phosphate solubilizing bacterial isolates, we used a buffered media for estimation of the organic acid profiles. The results revealed that apart from gluconic acid, malic acid is produced in significant levels by phosphate solubilizing bacterial isolates, and there seems to be a differential pattern of production of these two organic acids by the isolates in the presence of different insoluble phosphate sources.


Soil Systems ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 26
Author(s):  
Rihab Djebaili ◽  
Marika Pellegrini ◽  
Massimiliano Rossi ◽  
Cinzia Forni ◽  
Maria Smati ◽  
...  

This study aimed to characterize the halotolerant capability, in vitro, of selected actinomycetes strains and to evaluate their competence in promoting halo stress tolerance in durum wheat in a greenhouse experiment. Fourteen isolates were tested for phosphate solubilization, indole acetic acid, hydrocyanic acid, and ammonia production under different salt concentrations (i.e., 0, 0.25, 0.5, 0.75, 1, 1.25, and 1.5 M NaCl). The presence of 1-aminocyclopropane-1-carboxylate deaminase activity was also investigated. Salinity tolerance was evaluated in durum wheat through plant growth and development parameters: shoot and root length, dry and ash-free dry weight, and the total chlorophyll content, as well as proline accumulation. In vitro assays have shown that the strains can solubilize inorganic phosphate and produce indole acetic acid, hydrocyanic acid, and ammonia under different salt concentrations. Most of the strains (86%) had 1-aminocyclopropane-1-carboxylate deaminase activity, with significant amounts of α-ketobutyric acid. In the greenhouse experiment, inoculation with actinomycetes strains improved the morpho-biochemical parameters of durum wheat plants, which also recorded significantly higher content of chlorophylls and proline than those uninoculated, both under normal and stressed conditions. Our results suggest that inoculation of halotolerant actinomycetes can mitigate the negative effects of salt stress and allow normal growth and development of durum wheat plants.


2021 ◽  
Vol 13 (14) ◽  
pp. 8030
Author(s):  
Shehzad Mehmood ◽  
Amir Abdullah Khan ◽  
Fuchen Shi ◽  
Muhammad Tahir ◽  
Tariq Sultan ◽  
...  

Plant growth-promoting rhizobacteria play a substantial role in plant growth and development under biotic and abiotic stress conditions. However, understanding about the functional role of rhizobacterial strains for wheat growth under salt stress remains largely unknown. Here we investigated the antagonistic bacterial strain Bacillus aryabhattai PM34 inhabiting ACC deaminase and exopolysaccharide producing ability to ameliorate salinity stress in wheat seedlings under in vitro conditions. The strain PM34 was isolated from the potato rhizosphere and screened for different PGP traits comprising nitrogen fixation, potassium, zinc solubilization, indole acetic acid, siderophore, and ammonia production, along with various extracellular enzyme activities. The strain PM34 showed significant tolerance towards both abiotic stresses including salt stress (NaCl 2 M), heavy metal (nickel, 100 ppm, and cadmium, 300 ppm), heat stress (60 °C), and biotic stress through mycelial inhibition of Rhizoctonia solani (43%) and Fusarium solani (41%). The PCR detection of ituC, nifH, and acds genes coding for iturin, nitrogenase, and ACC deaminase enzyme indicated the potential of strain PM34 for plant growth promotion and stress tolerance. In the in vitro experiment, NaCl (2 M) decreased the wheat growth while the inoculation of strain PM34 enhanced the germination% (48%), root length (76%), shoot length (75%), fresh biomass (79%), and dry biomass (87%) over to un-inoculated control under 2M NaCl level. The results of experiments depicted the ability of antagonistic bacterial strain Bacillus aryabhattai PM34 to augment salt stress tolerance when inoculated to wheat plants under saline environment.


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